class template
<functional>
std::not_equal_to
template <class T> struct not_equal_to;
Function object class for non-equality comparison
Binary function object class whose call returns whether its two arguments compare not equal (as returned by operator operator!=).
Generically, function objects are instances of a class with member function operator() defined. This member function allows the object to be used with the same syntax as a function call.
It is defined with the same behavior as:
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template <class T> struct not_equal_to : binary_function <T,T,bool> {
bool operator() (const T& x, const T& y) const {return x!=y;}
};
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template <class T> struct not_equal_to {
bool operator() (const T& x, const T& y) const {return x!=y;}
typedef T first_argument_type;
typedef T second_argument_type;
typedef bool result_type;
};
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Objects of this class can be used on standard algorithms such as mismatch, search or unique.
Template parameters
- T
- Type of the arguments to compare by the functional call.
The type shall support the operation (operator!=).
Member types
member type | definition | notes |
first_argument_type | T | Type of the first argument in member operator() |
second_argument_type | T | Type of the second argument in member operator() |
result_type | bool | Type returned by member operator() |
Member functions
- bool operator() (const T& x, const T& y)
- Member function returning whether the arguments compare not equal (
x!=y
).
Example
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// not_equal_to example
#include <iostream> // std::cout
#include <functional> // std::not_equal_to
#include <algorithm> // std::adjacent_find
int main () {
int numbers[]={10,10,10,20,20};
int* pt = std::adjacent_find (numbers, numbers+5, std::not_equal_to<int>()) +1;
std::cout << "The first different element is " << *pt << '\n';
return 0;
}
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Output:
The first different element is 20
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See also
- equal_to
- Function object class for equality comparison (class template)
- greater
- Function object class for greater-than inequality comparison (class template)
- less
- Function object class for less-than inequality comparison (class template)
- greater_equal
- Function object class for greater-than-or-equal-to comparison (class template)
- less_equal
- Function object class for less-than-or-equal-to comparison (class template)